WASHINGTON, Aug 23 (Reuters) - SpaceX's attempt at the first ever private spacewalk next week will be a test of trailblazing equipment, including slim spacesuits and a cabin with no airlock, in one of the riskiest missions yet for Elon Musk's space company. A billionaire entrepreneur, a retired military fighter pilot and two SpaceX employees are poised to launch on Tuesday aboard a modified Crew Dragon craft, before embarking on a 20-minute spacewalk 434 miles (700 km) into space two days later.... Far outside the protective bubble of Earth's atmosphere, the electronics and shielding on Crew Dragon and spacesuits will...